Kimura Lock
In Judo it is called Gyaku Ude-Garami (Reverse Arm Entanglement). In Brazilian Jiu-Jitsu it's called the Kimura, named in honor of Masahiko Kimura, a Japanese Judo Champion that defeated Helio Gracie with this Shoulder Lock.
The Kimura Lock is a Submission Lock that locks the elbows and shoulders. The Kimura can do some damage, so if your practicing it on someone take it slow. Because if the Kimura is done at full tilt you can dislocate someones shoulder and rupture elbow ligaments.